Question

What is suggested by the similarity of early embryos of different species of vertebrates?

a. recent common ancestryb. evolution from a distant common ancestorc. no evolutionary relationship between the groupsd. similar environments in the past

Answer 1

The correct answer is - b. evolution from a distant common ancestor.

The early embryos very often do not resemble the physical appearance of their parents. They tend to have an appearance and features that look much more like some other species or group of animals. That slowly changes though as the embryo matures, gradually taking the shape and physical appearance of its parents.

The early embryos do not have the tendency of relatively quick change as the evolution goes on, but instead, they can have the same features as some very distant ancestor, even from tens of millions of years ago. This suggest that the parents of the embryo, as well as the embryo itself has a distant common ancestor with other species that have that appearance.

We can take the birds as an example. The early embryos of the birds have tails, instead of beak, they have a jaw with tiny sharp teeth, and their appearance is very reptilian. In fact, the birds are related with the reptilians, though that connection dates way back in the geological past.

Answer 2

The correct answer is: evolution from a distant common ancestor.

It has been shown that most of vertebrate embryos such as fish, reptiles, amphibians, birds, and mammals’ embryos begin with a basically similar structure: they have gill arches, notochords, spinal cords, and primitive kidneys. This happens because they share ancient genes that ere expressed during a middle "phylotypic period" of embryonic development.